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References: <20221029074654.203153-1-zyytlz.wz@163.com> <5882bd80983ac04a32676f07622cba7d0e245e55.camel@redhat.com>
In-Reply-To: <5882bd80983ac04a32676f07622cba7d0e245e55.camel@redhat.com>
From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Tue, 7 Mar 2023 12:24:58 +0800
Message-ID: <CAJedcCxmnnrVsq6TtyNPp1v7yv6hszbWnRub8V=ZNFA7OaFa=g@mail.gmail.com>
Subject: Re: [PATCH] drm/nouveau/mmu: fix use-after-free bug in nvkm_vmm_pfn_map
To:     Lyude Paul <lyude@redhat.com>
Cc:     Zheng Wang <zyytlz.wz@163.com>, nouveau@lists.freedesktop.org,
        bskeggs@redhat.com, kherbst@redhat.com, airlied@gmail.com,
        alex000young@gmail.com, security@kernel.org, daniel@ffwll.ch,
        Julia.Lawall@inria.fr, linux-kernel@vger.kernel.org
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Hi,

This bug has been proved to be a false positive. So there is no need
to make the patch.

Thanks,
Zheng

Lyude Paul <lyude@redhat.com> =E4=BA=8E2023=E5=B9=B43=E6=9C=887=E6=97=A5=E5=
=91=A8=E4=BA=8C 08:11=E5=86=99=E9=81=93=EF=BC=9A
>
> Actually - could you resend this with dri-devel@lists.freedesktop.org add=
ed to
> the cc list just to make patchwork happy?
>
> On Sat, 2022-10-29 at 15:46 +0800, Zheng Wang wrote:
> > If it failed in kzalloc, vma will be freed in nvkm_vmm_node_merge.
> > The later use of vma will casue use after free.
> >
> > Reported-by: Zheng Wang <hackerzheng666@gmail.com>
> > Reported-by: Zhuorao Yang <alex000young@gmail.com>
> >
> > Fix it by returning to upper caller as soon as error occurs.
> >
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> > ---
> >  drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gp=
u/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > index ae793f400ba1..04befd28f80b 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > @@ -1272,8 +1272,7 @@ nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, =
u64 addr, u64 size, u64 *pfn)
> >                                                      page -
> >                                                      vmm->func->page, m=
ap);
> >                       if (WARN_ON(!tmp)) {
> > -                             ret =3D -ENOMEM;
> > -                             goto next;
> > +                             return -ENOMEM;
> >                       }
> >
> >                       if ((tmp->mapped =3D map))
>
> --
> Cheers,
>  Lyude Paul (she/her)
>  Software Engineer at Red Hat
>